units only does multiplicative scale changes; thus it can convert Kelvin to
Rankine, but not Celsius to Fahrenheit. Most familiar units, abbreviations, and metric
prefixes are recognized, together with a generous leavening of exotica and a
few constants of nature including:

pi

ratio of circumference to diameter,

c

speed of light,

e

charge on an electron,

g

acceleration of gravity,

force

same as g,

mole

Avogadro's number,

water

pressure head per unit height of water,

au

astronomical unit.

Pound is not recognized as a unit of mass; lb is. Compound
names are run together, (for example, lightyear). British units that differ from
their U.S. counterparts are prefixed thus: brgallon. For a complete list of units,
type: